1. Field of the Invention
The present invention relates to a method for joining a node to a subnet of a communication network using an open communication medium while preventing home code overlap. More particularly, the present invention relates to a method of providing an identifier for identifying the subnet of an existing node to a node being joined to the subnet.
2. Discussion of the Related Art
Open communication mediums are communication mediums that are not only distributed within a predetermined control range, but also extend outside the predetermined control range. Accordingly, open communication mediums (e.g., a power lines) enable nodes within a predetermined control range to communicate with other node outside the predetermined control range.
Subnets (e.g., home networks) are portions of communication networks and comprise nodes (e.g., electronic appliances) that may communicate with each other via the aforementioned open communication medium. Generally, electronic appliances have a specific control range and may communicate with other electronic appliances within their specific control range via power lines found within a home network.
Communication between electronic appliances within a home network via power lines (i.e., power line networking) has been widely supported primarily because power line networking does not require extra communications mediums.
Power line networking requires electronic appliances within the specific control range transmit and receive data packets through power lines using a transceiver (e.g., a carrier-current transceiver). Further, power line networking requires the electronic appliances to be connected to an external communication network, such as the Internet, through a gateway.
Power lines within a home network do not constitute a closed distribution network within the specific control range but, rather, constitute an open distribution network (i.e., a network that branches from a power transmission site to each house network). Typically, data packets are transmitted between electronic appliances within open networks by employing broadcasting methods (i.e., transmission methods not using routers). Accordingly, data packets broadcasted by one electronic appliance within the specific control range are transmitted not only to other electronic appliances within the specific control range of the home network, but are also transmitted to electronic appliances existing outside the specific control range. Accordingly, open networks enable data packets transmitted from an electronic appliance in one house to be broadcasted to electronic appliances in other houses that are connected to the same power transmission site. One undesirable consequence of broadcasting within an open network occurs, however, when an electronic appliance located outside of a transmitting home network receives a command or other information within the broadcasted data packet in that the receiving appliance typically fails to function properly.
One method, proposed in order to solve the aforementioned problem, involves the installation of a blocking filter on a power line between the power transmission site and the home network. In theory, a blocking filter so installed could prevent data packets from being broadcasted to electronic appliances outside the transmitting home network. However, installing such a blocking filter is a relatively expensive solution to the aforementioned problem and it is often difficult to determine where an appropriate installation location exists. Moreover, information within data packets may still be leaked through other lines such as telephone lines, and the blocking filter may be improperly operated.
Data packets transmitted by electronic appliances found within home networks may include identifiers called home codes. Electronic appliances may selectively receive the transmitted data packets based on the identifier. For example, electronic appliances within the same home network must have the same identifier. Selection of a suitable identifier is essential to enable electronic appliances within a home network to communicate with each, according to their specific control range.
Methods for selecting a suitable identifier typically use hardware operating means, e.g., a dip switch. Using the hardware operating means, the identifier is selected by operating the dip switch prior to connecting the electronic appliance to a power line. As operating a dip switch may be difficult, an on-site service is usually provided by representatives of the electronic appliance companies wherein the representative confirms and adjusts the identifier for use within a particular home network. A problem still exists, however, that there is no proper method for detecting when an identifier selected in a first home network is identical to an identifier selected in a second home network, connected to the first home network by a power transmission site.
In order to solve the foregoing problem, the inventors of the present invention have disclosed “Power Line Communication Device Having Plug and Play Function” (non laid-open Korea patent application 10-2001-0011846, applied for registration on Mar. 7, 2001). The communication device disclosed in the non laid-open patent application includes a home code management module for managing a home code identifier that is uniformly provided to nodes existing within a specific control range among a plurality of nodes that are connected to a power line; an area code setup module for creating an area code identifier that is uniformly provided to nodes in the same area after the nodes existing within the control range are classified according to areas in which they exist; a group code setup module for creating a group code identifier that is uniformly provided to nodes of the same group by grouping the nodes existing within the control range according to predetermined correlations; and a device code management module for managing a device code identifier that is uniformly provided to each node. When power is connected to the respective nodes, the aforementioned modules automatically create a home code and an address to the nodes by broadcasting an identifier hail signal and receiving a response. While the aforementioned communication device solves problems related to dip switch operation, an algorithm used to detect and regulate home code overlap before generation of the home code is complicated.